Field of the Invention
The invention relates generally to the field of semiconductor memories and methods for managing them. In this context, the invention relates particularly to a memory management logic unit for extended use of read-only memories.
At present, programs are stored in microprocessor systems using, besides non-rewriteable read-only memories (ROMs), also rewriteable memories, such as RAMs or flash memories. In comparison with rewriteable memories, read-only memories can be produced inexpensively and, on account of easily implemented monolithic integration, afford faster access times and hence increased working speeds in the microprocessor systems. Since read-only memories are generally programmed using a mask for reasons of cost, it is not possible to alter their content again after manufacture. To be able to modify the stored data again after the memory has been manufactured too, rewriteable memories are also used instead of the read-only memories. These have the drawbacks over read-only memories described above, however.